Conversion of hydrocarbons with the use of a hydrogen fluoride composite catalyst



J. E. PENICK CARBON Aug. 12, 1952 2,606,860 OGEN CONVERSION OF HYDRO S WITH THE USE OF' A HYDR FLUORIDE COMPOSITE CATALYST 3 Sheets-Sheet l Filed May 24, 1949 J. E. PENlcK 2,606,860

S WITH THE USE OF A HYDROGEN FLUORIDE COMPOSITE CATALYST Aug. l2, 1952 CONVERSION OF' HYDROCARBON Filed May 24, 1949 5 Sheets-Sheet 2 6 .3 4 3 Z 1 0 btw@ bwwb IN V EN TOR. .fue E Panik/ BY /ENT W70/PNE?" Aug. l2, 1952 J, E, PEN|CK 2,606,860

CONVERSION OF HYDROCARBONS WITH THE USE OF' A HYDROGEN FLUORIDE COMPOSITE CATALYST Filed May 24, 1949 3 Sheets-Sheet 5 NUMBER 0F P45555 176/0 [1S/.4R65

Y J2@ .6i l)Den/ffm wa M mi raf #froze/vir atenteci ug. 12, 1952 CONVERSION OF HYDROCARBONS WITH THE USE OF A HYDROGEN FLUORIDE COMPOSITE CATALYST Joe E. Penick, Woodbury, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, a

corporation of New York Application May 24, 1949, Serial No. 94,955

2 Claims.

The present invention relates to the conversion of hydrocarbons and, more particularly, to the conversion in liquid phase of mixtures of hydrocarbons having relatively low octane numbers to mixtures of hydrocarbon having relatively high octane numbers; the conversion being carried out in the presence of hydrogen fluoride and at elevated temperatures.

The treatment of mixtures of hydrocarbons with hydrogen fluoride probably was rst disclosed by Hofman, et al. in British patents, Nos. 292,932 and 292,933. These investigators (Brit. 292,932) proposed to treat petroleum fractions boiling Within the range of 122 to 437 F. with hydrogen fluoride at ambient temperature for 1 to 24 hours to remove olenic bodies.

Frey in U. S. Patent No. 2,403,649, discloses that hydrocarbon material consisting predominantly of saturated hydrocarbons when subjected to the action of a substantial proportion, 0.2 to 4 times by Weight, of concentrated hydrouoric acid at a suitable reaction temperature and pressure undergoes several types of reactions.

Ridgway et al. in U. S. Patent No, 2,454,615, have disclosed that when gas oil, either virgin gas oil or recycle gas oil, is treated at elevated temperatures of 212 to 446 F. and preferably 284 to 349 F. for 2 to 4 hours, the gas oil is cracked to about 39 per cent gaseous products about 12 per cent gasoline (Cs-200 C.) and the balance about 49 per cent tar. These investigators also point out that, While the foregoing results are obtained when employing an oil to hydrogen fluoride ratio of l to 2.95 (by Weight) the amount of tar produced is increased when the ratio is decreased. Thus, when the ratio of oil to hydrogen fluoride is l to 1.93 (by weight), the total gas produced is 3l per cent, the gasoline is about 16 per cent and the tar is about 53 per cent. It has now been discovered that several factors other than oil to acid ratio and reaction temperature aiect the results produced when hydrocarbons are treated with hydrogen fluoride at elevated temperatures. For example, it has been discovered that when less than 3 parts by volume of acid is used per volume of oil to be treated improved results are obtained. This is in direct contradictionof the results obtained by Ridgway et al. In fact it has been found that best results are obtained when treating a naphtha by using an amount of hydroiluoric acid more than that required to saturate the hydrocarbon charge With hydrogen uoride but not exceeding about 2 volumes of hydrouoric acid per volume of charge stock.

It has also been discovered that a per cent or better ultimate yield of liquid product having a per cent point below the l0v per cent point of the charge stock can be obtained in a multi-pass operation when the conversion per pass is less than 40 per cent say of the order of 20 per cent to 30 per cent or less. Such conversion'sa're' obtained when the residence time is of the order of ten minutes or less, say 2 to 5 minutes. l j

Furthermore, it has been found that the concentration of acid soluble organic matter in the acid, hereinafter termed acid soluble oil, is effective in producing improved'results.

Finally, although the conversion is a liquid phase conversion; i. e., both the chargeY stock and the hydrouoric acid are in the liquid state, that the pressure under which the reaction proceeds, has an effect upon the quality of the products produced.

In general, .the present method provides for the treatment of mixtures of hydrocarbons, especially naphthas, with hydrogen uoride in liquid state in amounts greater than thatrequired to saturate the hydrocarbon charge with hydrogen fluoride and not moreY than in' the ratio of 2 volumes of hydrouoric acidto 1` volume of hydrocarbon charge stock atftemperatures of the order of 270 F. to 470 F. and preferably in the range of 320 F. to 450 F.

It has been found that the hydrofluoric acid should con'tain at least 4 per cent by Weight and not more than about 40 per cent by weight of acid soluble oil and not more than about 10 per centv of water. Y

It has been found that. generally, the hydrocarbon stool; at room temperature is saturated with hydrogen uoride when a. concentration of about 0.5 per cent hydrogen fluoride is attained. Consequently, an amount of hydrogen fluoride in excess of about 0.5 per cent by weightjoi the hydrocarbon charge is in excess of that amount required to saturate the hydrocarbon charge.Y

Although any mixture of hydrocarbons can be treated, the present method is very readily illustrated by discussion of the treatment of naphthas. Thus, for example, the treatment of naphthas having a boiling range of about 250. to 400 F. and naphthas having a boiling range of about 315 to 400 F. Will be used to illustrate the basic principles of the present method of converting hydrocarbons.

As shown in a more or less diagrammatic manner in Fig. I, the fresh hydrocarbon charge from a source not shown is passed Vby means of'line I0 through heat exchanger Il and line`l2 torre- 'sired product.

The reaction mixture comprising reactants,

catalyst and reaction products is passed via line l5 to settler IB. In settler I6 the hydrogen fluoride phase is the lower phase and is drawnoff through line l1 by pump I8.

The hydrocarbon products being lighterthan the hydrofluoric acid phase form the upper layer in settler iB and are withdrawn through line I9 pressure reducing valve 29 and line 2i to the mainfra'ctionating tower 22 in which the hydrocarbon products, whose 90 per cent point is at least below the 10 `per cent point of the charge stock Yand saturated with hydrogen uoride, are

kwithdrawn through line 23, heat exchanger 24 and line 25 tothe hydrogen -fluoride stripper 26. The remaining higher boiling hydrocarbons are withdrawn from fractionating column 22 through line 21 by pump 2B and recycled to the reactor I3 through lines 29 and l2.

Inthe stripper 2B hydrogen fluoride and light hydrocarbons are taken as overhead and passed through line 30, heat Aexchanger 3i and line 32 to settler 33 in which the hydrogen nuoride forms the lower liquid phase and the light hydrocarbons the upper liquid phase.

The hydrocarbon phase in settler 39 is returned through line 34 to stripper 26 to serve as reflux while the hydrogen fluoride is withdrawn from settler 33through line 35 to line nt.

The hydrogen fluoride phase withdrawn from settler I6 through line kil in part is transferred 5to the hydrogen fluoride regenerator 3l in which hydrogen fluoride is taken as overhead through Y line 38and heat exchanger 39 and with the hydrogen fluoride vfrom settler 33 returned through lines and i4 to the reactor I3.

Returning now to the hydrogen iluoride stripping operation, the'overhead from stripper 25 is hydrogen fiuoride andlight fractions of the de- This overhead is withdrawn as described hereinbefore through line3. The bottoms; i. e., the desired product having a 90 per cent point lower than the 10 per cent point of the 'charge stock `vis withdrawn from stripper 23 through line 40 to storage or for further treatmentpor other use as the situation requires.

The 'foregoing has been a description of the general operation of the present method. However, certain factors affect the results of the present method of converting hydrocarbons and require discussion. Thus, `for example, it has been established that the acid to hydrocarbon; i. e., hydrofluoric acid to charge stock ratio has amarked effect upon the amount of high boiling or'tarry material produced. This is aptly illustrated by the curves of Fig. II. The materials treated to illustrate this effect were two naphthas; Vone having a `boiling range of 250-400 F. and the other having a boiling range-of 3152409 F. The curves of Fig. II establish that as the 'ratio of hydrogen fluoride to charge stock is increased from about 0.4 Yto 5.0 volumes of hydrouoric acid per volume of charge stock the ratio Soi converted raffinate -i. e., materialhaving a 90 per cent point below the 10 per cent point of the charge stock, to organic material soluble in the hydroiluoric acid phase; i. e., tarry material, decreases from 6 to 1 to l to 1. In other words, when treating a charge stock at a given temperature and under a pressure sufficient to maintain the reactants in the liquid phase, the ratio of desired products to undesirable products decreases as the ratio of hydrouoric acid to charge stock decreases. Thus, at a HF:HC ratio of 0.4-0.5 volumes to 1 volume, the volume of the hydrocarbon product was 6 times the volume of the acid soluble oil. In contrast, when 3 volumes of hydrofluoric acid were used per l volume of charge, the ratio of desired product to acid soluble oil was 1 to l. The foregoing can be stated in another manner. When the hydroiluoric acid to charge stock ratio was 0.4-0.5:1 the desired product was about 86 per cent of the charge stock converted and the acid soluble oil about i4 per cent. However, when the hydroiiuoric acid to charge stock ratio was 3:1, 'about 54 per cent of the charge was converted to rdesired product and about 46 per cent to acid soluble oil. Y

It is interesting to contrast the results obtained by Ridgway et al. with those ob-tained in the present method. At an acid to charge stock ratio of 2.95 to l, 50 per cent of the charge stock was'converted to gas and gasoline while 49.7 per cent was converted to tar. -At an acid to charge stoel: ratio of 1.93 to l Ridgway et al. obtained 46.9 per cent gas and gasoline and 53.1 per cent was converted to tar. At or about the same acid to charge stock ratios the present method converts 67 and 60 percent of the charge stock respectively to ranate and the balance to acid soluble oil. Thus, the results produced by the present method are diametrically opposed to those obtained in the prior art process.

The curves in Fig. HI establish that in the treatment of naphthas as the ratio of acid to charge stock is increased from about 0.5 to about 4.6 to l (by volume), the ultimate conversion decreases from about 90 per cent to about 55 per cent.

The foregoing leads to the expression of the preferred conditions as those in which the ratio of hydrofluoric acid or hydrogen fluoride to charge stock is not greater than about 2.5 to 1 and not less than an excess of that amount of hydrogen fluoride required to saturate the charge stock therewith.

A further modification of the basic concept is control of the water and soluble oil content of the catalytic hydrofluoric acid. It has 'been Afound that improved results are obtained when the acid contains at least 4 per cent by weight of organic material soluble in the acid catalyst and termed herein acid soluble oil. Figs. -IV and V illustrate the fact that with fresh hydrofluoric acid about 9.2 per cent of the charge-is converted to organic material soluble in the acid; i. e., acid soluble oil although that represents only about 4 weight per cent of the acid phase. When that acid is recycled only about 8 weight per. cent of the charge is converted to acid soluble oil in the second pass and about 5 weight per cent in the third and subsequent passes, although the total amount of acid soluble oil reaches about 9 weight per cent of the acid phase in the fourth and subsequent passes. In other words, whenthe hydroiuoric acid contains about 8 to about 10 weight per centY of acid soluble oil, the conversion 'of charge stock to acid soluble oil is aminimum.

Table Charge stock-314-400 F. Heavy naphtha. Reaction temperature-340 F. Contact time-about 7 minutes. HF/HC ratio (Volume) 0.5:1.

Vapor pressure of conversion products at reaction temperature-780 p. s. i.

Reaction pressure 1600 p. s. i. 900 p. s, i. Pressure differential-" 820 p. s.i 129 p. s. i. Charge stock octane number 18.0 18.0 Octane number of conversion gaso1ine 77.2 70.0 Ultimate yield, vol. per

cent of charge 80 68 It is manifest' that not only is the improvement in octane number markedly greater but the ultimate yield of gasoline is about 18 volume per cent greater as a result of operating'at a reaction pressure greater than about 150 p. s. i. greater than the vapo;- pressure o-f the conversion products.

The residence time for the conversion reaction varies with the temperature and in general is less the higher the temperature within the interval 270 F. to 470 F. The preferred conditions are a reaction temperature of about 300 F. to 450 F., a residence time sufficient to secure not more than about 40 volume per cent conversion to products having a 90 per cent point lower than the 10 per cent point of the charge stock and preferably a residence time suicient to obtain only about 20 to 30 per cent conversion to products having a 90 per cent point lower than the 10 per cent point of the charge stock. In general, a residence time of not more than 20 minutes and preferably of the order orf-2 to 10 minutes dependent upon the reaction temperature is desirable. With the reaction conditions described hereinbefore, satisfactory results will be obtained employing at least suiiicient hydroiiuoric acid to form a second liquid phase; i. e.,

an amount in excess of that required to saturate the charge stock with hydrofluoric acid and not more than about 2.5 Volumes of hydrouoric acid per volume of ch-arge stock and preferably about 0.4 volume to about 1.5 volumes of hydroiiuoric acid per volume of charge stock. The results described herein can only be obtained when the reactants are in the liquid state. Consequently, the conversion reaction must be carried out at a pressure at least sufficient at the reaction temperature to maintain liquid state conditions and preferably at least 150 pounds per square inch (p. s. i.) higher than the vapor pressure of the eiuent from the reactor at the reaction temperature.

While thepresent' conversion method may be carried out with total recycle or without recycle of the hydrouoric acid, it is preferred to recycle at least 25 per cent of the hydrofluoric acid. Similarly, while 100 per cent hydroluoric acid may be used and the concentration of hydrogen fluoride in the catalytic acid should be more than 50 per cent with a maximum of 10 per cent of waterl it is preferred that the acid catalyst contain not more than 5 per cent of water and at least 4 per cent of soluble organic material herein termed acid soluble oil. Thus, acid cataylst containing not more than 5 per cent water and preferably less than 3 per cent water and having a titratable acidity of at least 50 per cent to about 90 per cent hydrogen iiuoride gives satisfactory results.

We claim:

1. A method of converting a mixture oi normally liquid hydrocarbons into a liquid product having a 90% point below the 10% point of said hydrocarbon mixture which comprises contacting for about 2 to 5 minutes a mixture of normally liquid hydrocarbons with a catalyst consisting essentially of not more than 10% Water, about 4 to about 10% hydrogen fluoride-soluble oil and the balance hydrogen fluoride in the ratio of about 0.25 to 2.0 volume of said catalyst per volume of said hydrocarbon mixture at a temperature of about 200 F. to about 470 F. at a pressure at least 150 p. s. i. greater than the vapor pressure of the reaction mixture, separating a hydrocarbon phase from said liquid catalyst, and recovering from said hydrocarbon phase a liquid product having a 90% point below the 10% point of the charged mixture of hydrocarbons in an ultimate yield of at least of said charged mixture.

2. A method of converting a naphtha into a liquid product having a point below the 10% point of said naphtha which comprises contacting for about 2 to 5 minutes a naphtha with a catalyst consisting essentially of not more than about 5% Water, about 8 to about 10% hydrogen fluoride-soluble oil and they balance hydrogen fluoride in the ratio of about 0.25 to 2.0 volume of said catalyst per volume of naphtha at a temperature of about 200 to 470V F. at a pressure at least p. s. i. greater than the vapor pressure of the reaction mixture, separating a hydrocarbon phasel from said liquid catalyst, and recovering from said hydrocarbon phase a liquid product having a 90% point below the 10% point of said naphtha in an ultimate yield greater than 75% of said charged naphtha.

JOE E. PENICK.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,449,463 Evering et al Sept. 14, 1948 2,450,588 Evering et al. Oct. 5, 1948 2,454,615 Ridgway et a1. Nov. 23, 1948 2,495,133 Ridgway Jan. 17, 1950 2,501,023 Brandt et al. Mar. 21, 1950 

1. A METHOD OF CONVERTING A MIXTURE OF NORMALLY LIQUID HYDROCARBONS INTO A LIQUID PRODUCT HAVING A 90% POINT BELOW THE 10% POINT OF SAID HYDROCARBON MIXTURE WHICH COMPRISES CONTACTING FOR ABOUT 2 TO 5 MINUTES A MIXTURE OF NORMALLY LIQUID HYDROCARBONS WITH A CATALYST CONSISTING ESSENTIALLY OF NOT MORE THAN 10% WATER, ABOUT 4 TO ABOUT 10% HYDROGEN FLUORIDE-SOLUBLE OIL AND THE BALANCE HYDROGEN FLUORIDE IN THE RATIO OF ABOUT 0.25 TO 2.0 VOLUME OF SAID CATALYST PER VOLUME OF SAID HYDROCARBON MIXTURE AT A TEMPERATURE OF ABOUT 200* F. TO ABOUT 470* F. AT A PRES- 